This invention relates to a method and an apparatus for transporting coiler cans in a spinning plant between a sliver producing machine (such as a carding machine) and a sliver consuming machine (such as a drafting frame) and/or an intermediate station by means of a transporting carriage which is associated with a loading and unloading device whose gripping and conveying elements are linearly shifted. The gripping elements serve the purpose of grasping the coiler can whereas the conveying elements transfer the coiler cans to or from the transporting carriage.
In a conventional method, by means of a loading and unloading device mounted on the transporting carriage, a coiler can filled with sliver or an empty coiler can is transferred to or is taken from the transporting carriage. The gripping device has two horizontal telescoping cylinders having respective pistons. At the end of one piston a pressure cylinder is provided at an angle of 90.degree. which operates in a direction radial to the coiler can and firmly clamps the coiler can against the oppositely located other pressure cylinder. For adapting the gripping device to the round outer surface of the coiler can, two curved, short clamping pieces are provided. First, the clamping pieces are shifted in a linear direction tangentially relative to the coiler can in such a manner that the coiler can is placed between the clamping pieces. Between the clamping pieces and the lateral coiler can surface only narrow spaces remain. The clamping pieces are short to ensure that the can fits therebetween when it is grasped. The stroke of the pressure cylinder which is mounted transversely on a horizontal telescoping cylinder is also short. Thereafter the coiler can is, as the pressure cylinder moves radially in the direction of the coiler can, radially frictionally firmly grasped by the clamping pieces.
In the above-outlined grasping process the gripping of the coiler cans requires a very accurate positioning of the transporting carriage at the coiler can stand, because each coiler can has to be positioned (in the x-direction) with very small lateral distances in the intermediate space between the two clamping pieces which face one another. In addition, the telescoping cylinders with the clamping pieces must also be very accurately positioned relative to the coiler can (y-direction) to ensure that the short clamping pieces securely grasp the outer surface of the coiler can. Such an accurate positioning of the clamping pieces in the longitudinal and transverse directions is complicated and may easily lead to operational disturbances.